The present invention relates generally to containers for multi-component compositions, and more specifically to a container for settable compositions, such as wallboard joint compound.
Walls and ceilings made from gypsum wallboard are conventionally constructed by attaching the wallboard panels to framing members or studs, and filling and coating the joints between the panels with a specially formulated paste composition called a joint compound. Joint compounds may be supplied as powdered compositions (to be mixed with water at the jobsite) or may be premixed with water at the factory to yield a ready mixed (or paste) joint compound. A paste joint compound (Taping grade) is placed within and over the joint formed by the abutting edges of the wallboard panels, and a paper reinforcing tape is embedded in the joint with the joint compound which is then permitted to dry. Alternately, the reinforcing tape may be of non-cellulose composition, but of a size and shape similar to strips of paper joint tape. Alternately, the reinforcing tape may be of a fiberglass weave requiring the use of chemically setting type joint compounds. When the joint compound is dry, a second joint compound (Topping or Finishing grade) is applied over the joint, and it too is permitted to dry. It is usually necessary for a third application of a joint compound and, after the third coat is dry, it may be lightly sanded and may be conventionally finished with a decorative material (paint, texture or wallpaper) then applied to the wall. All three coats of joint compound may alternately be done with an All Purpose grade of joint compound.
Ready mixed joint compound is typically supplied to the customer in either cardboard cartons or plastic pails in units typically with volumes of 3.5 to 4.5 gallons (13.25-17.03 L) for large applications, or 1 to 3.5 quarts (0.95-3.31 L) for smaller applications. Joint compound is supplied at a viscosity typically higher than what is applied at the jobsite. This allows the contractor to mix in additional water using a power drill and mixing paddle to achieve the desired application viscosity.
Ready Mix joint compound production is typically accomplished by blending the wet and dry ingredients in a mixer until smooth, adjusting the viscosity to a desired level through water addition, then filling and sealing containers to be shipped to customers. This process can be disrupted by use of ingredients which thicken very rapidly and take longer periods of time to fully wet out and drop in viscosity, leaving the combined wet and dry ingredients in the mixer competing for water through the typical mixing cycle and at a higher than desired viscosity. The above process results in mechanical limitations and problems such as binding of the wet mixer and overloading of the mixer motor. The higher than desired viscosity at the completion of the mixing cycle affects the ease of pumping and moving the material out of the mixing system and through the packaging line and also interferes with the lidding and closing of the container.
Thus, there are mechanical limitations on the types of raw materials that can be used within a typical wet mixing system for manufacturing ready mix. Depending on the particular product requirements, including long pre-use shelf life, fast setting, low viscosity of application and others, several options have been proposed to provide joint compounds with separated additives that enable the user to obtain enhanced or more desirable joint compound performance characteristics when the mixture is finalized just prior to application. U.S. Pat. No. 6,476,099, incorporated by reference, discloses the addition of surfactant additives to joint compound to generate performance with improved cracking, improved shrinkage and reduction of surface finish defects after application to wallboard surfaces. U.S. Pat. Nos. 6,228,163 and 5,746,822 also incorporated by reference, disclose joint compounds formulated with a base joint compound that is relatively inert until an extra additive is provided, functionally serving as an activator.
U.S. Pat. No. 8,822,566, incorporated by reference, discloses providing a nonhomogeneous formulation of an additive with a ready mix base joint compound for ultimate mixing by the user on the jobsite.